28 research outputs found
Étude du régime alimentaire de deux souches de truite arc-en-ciel marocaine et bulgare dans deux plans d'eau du Moyen-Atlas Amghass I et Amghass II
Le présent travail porte sur l'étude du régime alimentaire de deux souches de truites arc-en-ciel : la souche marocaine issue de croisements de truites arc-en-ciel en provenance d'Europe et d'Amérique du nord et la souche bulgare introduite au Maroc en 1987. Les milieux d'étude sont deux plans d'eau du Moyen-Atlas marocain (Amghass I et Amghass II) présentant des eaux de bonne qualité physique et chimique et une diversité biologique (invertébrés) assez importante. Afin de déterminer les préférences alimentaires de ces deux souches nous avons évalué : le spectre alimentaire, déterminé par les abondances relatives, les coefficients d'occurrence des proies ingérées, l'indice alimentaire de Lauzanne pour les différentes catégories de proies et l'intensité de prédation des truites.Les résultats ont montré une similitude au niveau des régimes alimentaires des deux souches caractérisés par une nette préférence pour les larves et nymphes d'Insectes considérées comme proies essentielles.This current work is about the study of the dietary regime of two species of rainbow trout. The Moroccan kind is a cross breed of the European and North American Rainbow trout and the Bulgarian trout introduced into Morocco since 1987.The environments of study are two stretches of water in the "Moyen-Atlas" (Amghass I and Amghass II), which present water of good physical and chemical quality and are of quite important biological diversity.To determine the dietary preferences of the two species, we evaluated several parameters: the dietary spectrum which is determined by the relative abundance and the coefficient of occurence of ingested prey, the index alimentary of Lauzanne for the different categories of prey and how predatory the trout areThe results have shown a similarity in the level of dietary regimes of the two populations outlined by a clear preference for larvae and nymph insects which are considered to be essential prey
Contribution à l'étude du régime alimentairedu barbeau (Barbus barbus callensis Valenciennes, 1842) d'un cours d'eau du Moyen-Atlas (Maroc) : Oued Boufekrane
L'étude du régime alimentaire du barbeau (Barbus barbus callensis Valenciennes, 1842) de l'Oued Boufekrane a été réalisée sur 1 021 poissons, capturés entre janvier 1998 et juin 1999. Cette espèce présente un rythme saisonnier d'activité alimentaire. Ainsi, avec des faibles taux de vacuité, l'été et le printemps sont les saisons de forte activité alimentaire. Cette dernière diminue durant l'automne et l'hiver. Le caractère omnivore du barbeau est vérifié ; son régime alimentaire se compose essentiellement de larves d'Insectes et de débris de végétaux. Les jeunes individus (moins de 13 cm de longueur) ont une tendance zoophage, dominée par les larves de Diptères et d'Éphéméroptères. En revanche, les plus âgés présentent une tendance phytophage qui reflète l'opportunisme de ce poisson et explique ainsi, son adaptation aux conditions trophiques du milieu, caractérisées par une pauvreté en benthos.The diet of the barbel (Barbus barbus callensis Vallenciennes, 1842) in Boufekrane stream was studied on 1021 fish catched between January 1998 and June 1999.This species presented a seasonal rhythm. So, with the low rate of vacuity index, the summer and the spring were the seasons of intense alimentary activity. This activity regressed during automn and winter. The omnivorous character of the barbel was verified. The diet was composed essentially from insect larvae and plant's sherd. The young barbel (length is less than 13 cm) have zoophagous tendency. Their diet was dominated by Diptera and Ephemeroptera larvae. But, the old ones present a phytophagous tendency the opportunism of this species and the plasicity of its diet. This behavior explain the adaptability of this species to trophic conditions in the stream which contained low density of benthic fauna
Electrochemical Determination of Trichloroacetic Acid using Platinum Electrode
The electrochemical reduction of Trichloroacetic acid (TCA) on a platinum electrode by cyclic and linear sweep voltammetry was described. The measurements were investigated under optimized conditions. The supporting electrolyte was 0.01 M sodiumnitrate solution (pH 6.0), scan rate 50mV\s and the reached detection and quantification limits was 4x10-6 mol l-1. The obtained result indicated linear increasing of the current with concentration of TCAA between lower and upper detection limits and excellent sensitivity towards TCAA reduction, which demonstrates the analytical utility of platinum electrode. Meanwhile, interference from other ions and substances were examined. The experimental results indicate that the method for the determination of TCAA samples is successful comparing with other methods or techniques
Utilization Potential of Glass Fiber and Crumbled Rubber as Subgrade Reinforcement for Expansive Soil
Due to its high potential for volume change, expansive soil is a problematic building material that can cause harm to road infrastructure. The purpose of this study is to examine the effect of glass fiber and rubber on the properties of expansive soil and their suitability as subgrade reinforcement in road applications. For different percentages of glass fiber and rubber in the soil, the Maximum Dry Density (MDD), Optimum Moisture Content (OMC), and CBR were measured. The results demonstrated that the incorporation of glass fiber and rubber improved the soil's properties. With increasing fiber and rubber content, the MDD and CBR increased, while the OMC decreased. In addition, the strength of the reinforced soil was significantly greater than that of the unreinforced soil. The research indicates that the addition of glass fiber and rubber can improve the efficacy of expansive soil as subgrade reinforcement in road applications.
Doi: 10.28991/HEF-2023-04-03-06
Full Text: PD
Predicting survival of de novo metastatic breast cancer in Asian women: Systematic review and validation study
10.1371/journal.pone.0093755PLoS ONE94-POLN
Optimum spacecraft attitude control methods for a combined attitude and thermal control system
Spacecraft missions need efficient and precise attitude control systems. With the aim of reducing the vehicle volume and mass, and for a greater reliability, a system combining the conventional spacecraft attitude control and thermal control systems in a single system is proposed. The combined attitude and thermal control system (CATCS), which can work as an attitude actuator and as a heat pipe, uses the satellite’s excess heat to circulate an electric conductivity fluid in a circular closed duct. The fluid circulation provides an angular momentum that can be used for spacecraft attitude controls. The CATCS system is a maiden solution that combines both the attitude and thermal control systems. The feasibility of CATCS has been demonstrated in a previous study. However, the demonstration is dedicated to a single axis (pitch) attitude control capability using the proportional-integral (PI) controller. The proposed work focuses on improving the performance of the attitude control of LEO small satellites with the CATCS system as an actuator by applying a number of advanced control methods. The thermal control performances and properties are constant as in Ref. (Varatharajoo et al., 2003). In addition, there will be no thermal control degradation. A mathematical model of the satellite is represented based on the assumption that the satellite is a rigid body. First, the classical PI controller has been used for a 3-axis attitude control (roll, pitch and yaw). Then, four advanced control methods have been designed and tested to improve the attitude control performance of a small satellite using the CATCS system. The advanced controllers are: the Active Force Control (AFC) with PI controller (AFC-PI), H2 controller, H∞ controller, and the mixed H2/H∞ controller. The proposed controllers are designed to keep the attitude accuracy below the 0.2. The controllers were applied to a 3-axis satellite attitude control independently. The controllers together with their governing equations are coded in MATLAB and SIMULINKâ for both ideal and non-ideal system numerical simulations.
The analysis of the results shows that the H2 controller gives the best attitude control performance compared to the other tested controllers, while the PI controller gives the worst attitude control performance for the reference case. The AFC-PI controller shows much better responses than the solely PI controller. The mixed H2/H∞ control shows good attitude accuracies, while the H∞ control has low attitude accuracies compared to the other advanced controllers. The control gains of the designed controllers are small and reasonable except that of the H∞ controller. However, from the performance figures, it is clear that all the proposed controllers can efficiently provide a full 3-axis control with attitudes accuracies below 0.2. The attitude performances show that the CATCS attitude pointing accuracy can be improved through the proposed advanced control methods
Fabrication of an electrochemical sensor based on eggshell waste recycling for the voltammetric simultaneous detection of the antibiotics ofloxacin and ciprofloxacin
Abstract In this work, an accurate, highly sensitive, and economical electrochemical sensor based on a carbon paste electrode modified by Ca2CuO3 nanostructure (Ca2CuO3 NS) was constructed using Eggshell waste recycling as a cheap source of calcium. The Ca2CuO3 NS was analyzed using FTIR, SEM, and XRD measurements. The synthesized nanomaterials utilized for the first time to enhance the electrocatalytic efficiency of carbon paste electrode (CPE) toward fluoroquinolones antibiotics ofloxacin (OFL) and ciprofloxacin (CIP), The drugs used to treat pneumonia caused by COVID-19. The synthesized Ca2CuO3 NS dramatically enhanced the anodic peak response of CPE toward both drugs compared to the unmodified one and other modified electrodes. The simultaneous detection of the two antibiotics was performed in the linear range of 0.09–1.0 μM for OFL and 0.05–0.8 μM for CIP with the LOD of 0.027 μM and 0.012 μM, respectively. The suggested method was applied successfully to determine OFL and CIP in real samples
Corrosion resistance and electrodeposition behavior of electrodeposited nickel‐cobalt‐iron alloys
Prevalence of intestinal parasites and bacteria among food handlers in a tertiary care hospital
Objectives: The aim of this work is to determine the prevalence of intestinal parasites and bacteria among the food handlers. Materials and Methods: Two hundred food-handlers were subjected to a cross-sectional study working in the kitchen of a tertiary care hospital, i.e., Alnoor Specialist Hospital, Makkah, Saudi Arabia from February 2 to 27, 2009. The stool samples were examined for intestinal parasites following direct microscopic examination, formol ether concentration (Ritchie), and staining with modified acid fast staining techniques. For enteropathogenic bacteria samples were inoculated onto MacConkey′s agar, deoxycholate citrate agar, xylose lysine deoxycholate agar as per the World Health Organization protocol. Fingernail materials were examined microscopically for enteropathogenic bacteria and parasites. Results: The majority (80%) of the food-handlers were young adults aged from 22 to 42 years. No intestinal parasites were detected from fingernail contents. Forty six (23%) stool specimens were positive for intestinal paraͼsites. Giardia lamblia 18 (9%) was most frequent among the 10 different types of detected intestinal parasites followed by Entamoeba histolytica 9 (4.5%). No pathogenic bacteria were detected in all stool samples, whereas finger nails showed isolation of microorganisms as coagulase-negative staphylococci 79 (39.5%), followed by Staphylococcus aureus 35 (17.5%). Conclusion: The findings emphasized the importance of food handlers as potential sources of infections and suggested health institutions for appropriate hygienic and sanitary control measures